setDefaultPaymentMethod

The setDefaultPaymentMethod Firebase Cloud Function allows the owner of a subscription to set a specific payment method as the default for future invoices and payments.

Function Signature

export const setDefaultPaymentMethod = https.onCall(async (data: SetDefaultPaymentMethodData, context) => { ... });

Parameters

The function expects the following data in the data object:

SetDefaultPaymentMethodData Interface:

interface SetDefaultPaymentMethodData {
    subscriptionId: string;
    paymentMethodId: string;
}

Context

The function requires an authenticated user context (context.auth). The authenticated user must also be the owner of the specified subscription.

Behavior

1. Authentication Check: Verifies that the user calling the function is authenticated. If not, it throws an unauthenticated error.
2. Subscription Retrieval: Fetches the subscription document from Firestore using the provided subscriptionId.
   • If the subscription does not exist, it throws a not-found error.
3. Owner Verification: Checks if the authenticated user is the owner (owner_id) of the subscription. If not, it throws a permission-denied error.
4. Stripe Customer ID Retrieval: Retrieves the Stripe subscription to get the associated customer ID.
   • If no customer is found for the subscription, it throws a failed-precondition error.
5. Update Customer’s Default Payment Method: Calls the Stripe API to update the customer’s invoice_settings to set the provided paymentMethodId as the new default.
6. Success: Returns { success: true } upon successful update.

Error Handling

The function throws HttpsError with specific codes for different failure scenarios:

• unauthenticated: If the user is not authenticated.
• not-found: If the subscription is not found.
• permission-denied: If the user is not the subscription owner.
• failed-precondition: If no Stripe customer is found for the subscription.
• internal: For any Stripe API errors or other unexpected errors during execution.

Example Usage (Client-side)

import { getFunctions, httpsCallable } from 'firebase/functions';
import { getApp } from 'firebase/app';

const functions = getFunctions(getApp());
const setDefaultPaymentMethodCallable = httpsCallable(functions, 'setDefaultPaymentMethod');

async function callSetDefaultPaymentMethod(subscriptionId: string, paymentMethodId: string) {
    try {
        const result = await setDefaultPaymentMethodCallable({ subscriptionId, paymentMethodId });
        console.log('Default payment method set successfully:', result.data);
        // Expected result.data: { success: true }
    } catch (error) {
        console.error('Error setting default payment method:', error.code, error.message);
    }
}

// Example call
// callSetDefaultPaymentMethod('sub_your_stripe_subscription_id', 'pm_new_default_payment_method_id');